Control channel transmitting method, base station and terminal

ABSTRACT

A method used by a terminal in a wireless communication system, the method includes: receiving a control channel transmitted from a base station with use of a control channel format selected from among a plurality of control channel formats, each including modulation scheme information, according to whether Multiple Input Multiple Output (MIMO) transmission is applied or not, and wherein a number of bits indicating a modulation scheme included in a control channel format to be selected when the MIMO transmission is applied is greater than that included in a control channel format to be selected when the MIMO transmission is not applied.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.14/481,487, filed Sep. 9, 2014, now pending, which is a continuation ofU.S. application Ser. No. 14/258,143, filed Apr. 22, 2014, which is acontinuation of U.S. application Ser. No. 13/720,270, filed Dec. 19,2012 which is a continuation of U.S. application Ser. No. 11/812,789,filed Jun. 21, 2007 which is a continuation of Int'l., Appl. No.PCT/JP2004/019626, filed Dec. 28, 2004, the contents of each are hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control channel transmitting method,a base station and a terminal, in particular, to a control channeltransmitting method, a base station and a terminal for adaptivelycontrolling a communication parameter with the use of a control channel.

2. Description of the Related Art

For example, in a communication system in the third generation, adaptiveradio link control such as adaptive modulation/demodulation, HARQ(Hybrid Automatic Repeat request), scheduling or such is used, for thepurpose of improving data packet transmission efficiency. The adaptiveradio link control is carried out with the use of a separate or a sharedcontrol channel, and, a link parameter which is used in a data channeltransmitted approximately simultaneously with the control channel, isnotified of to each user terminal.

For example, in a case of the adaptive modulation/demodulation, thecontrol channel transmits information such as a data channel modulatingmethod, an encoding rate and so forth. In a case of the HARQ, thecontrol channel transmits information such as packet numbers of packetstransmitted via a data channel, the number of times of re-transmissionand so forth. In a case of the scheduling, the control channel transmitsinformation such as a user ID.

In HSPDA (High Speed Downlink Packet Access) standardized by 3GPP (ThirdGeneration Partnership Project), the shared control channel calledHS-SCCH (Shared Control Channel for HS-DSCH) is used, and controlinformation such as that shown in Table 1, is transmitted, as disclosedby a non-patent document 1.

TABLE 1 HS-SCCH physical channel Channelization-code-set information 7bits Modulation scheme information 1 bit  Transport-block sizeinformation 6 bits Hybrid-ARQ process information 3 bits Redundancy andconstellation version 3 bits New data indicator 1 bit  Ue identity 16bits 

In a control channel transmitting method in the prior art used in theadaptive radio link control, in order to positively demodulate thecontrol channel transmitting information required for data channeldemodulation on a reception side, a fixed control channel format isused. Further, in order to avoid degradation in data channeltransmission efficiency, an information amount is reduced to be bareminimum in the control channel transmitting method in the prior art, thecontrol channel format to be used is fixed, and thus, a variable controlchannel format is not used.

As disclosed in a non-patent document 2, HSDPA control information shownin Table 1 undergoes rate matching to be totally 120 bits, afterundergoing CRC attaching and convolution encoding of R=1/3. Then, QPSKmodulation and spreading of SF=128 are carried out, and mapping iscarried out in a physical channel of HS-SCCH.

-   Non-patent document 1: 3GPP TS 25.212 v5.9.0 (2004-06)-   Non-patent document 2: 3GPP TS 25.211 v5.6.0 (2004-09)

In a next generation communications system, in order to achievehigh-speed data transmission, MIMO (Multiple Input Multiple Output)transmission with the use of multi-carrier transmission or a pluralityof antennas is used. In this case, it is possible to further improvetransmission characteristics by carrying out adaptive control of a radioparameter for each sub-carrier or for each transmission antenna.

However, MIMO transmission has such a problem that the number ofvariable parameters increases, and the number of bits required for thecontrol channel increases. Further, also for a case where the number ofsimultaneously multiplexing users via one frame increases, requiredinformation of the control channel increases in proportion to the numberof users.

On one hand, the upper limit of a channel capacity simultaneouslytransmittable is defined by the number of channels which can bemultiplexed orthogonally. Accordingly, when the information amount ofthe control channel increases, the number of data channels available fordata transmission decreases, and as a result, the data transmissionefficiency degrades.

Description will now be made with a case of user multiplexing by meansof CDMA (Code Division Multiple Access) for example. FIG. 1 illustratesthe number of codes available for data channels when the number ofsimultaneously multiplexing users is 1. FIG. 1 shows an example in whichthe number of simultaneously multiplexing users is 1, and, codemultiplexing transmission of spreading of SF=8 is carried out for eachof both the data channels and the control channels. When the number ofcodes required for transmitting the control channels is 1, the number ofcodes available for the data channels is 7 as all the remaining coderesources which can be orthogonalized are used for the data channels.

FIG. 2 illustrates the number of codes available for data channels whenthe number of simultaneously multiplexing users is 4. When the number ofsimultaneously multiplexing users is 4 as in FIG. 2, 4 codes are usedfor the control channel, and thus, the number of codes available for thedata channels is limited to 4. Accordingly, the data channeltransmission efficiency per frame degrades in 4/7.

When the information amount of the control channel is reduced to be bareminimum in order to avoid degradation in the data channel transmissionefficiency, a benefit of the adaptive radio link control may not beobtained, and thus, the transmission characteristics of the entiresystem may not be improved.

For example, in wide band multi-carrier transmission, communicationquality differs for each sub-carrier due to frequency selective fading,and thus, it is possible to improve total throughput by carrying outcommunications with always selecting a sub-carrier having goodcommunication quality.

Further, the same in MIMO transmission, when independent fading for eachantenna branch occurs, it is possible to improve total throughput byalways selecting a transmission antenna having good communicationquality, or carrying out adaptive modulation/demodulation for eachantenna. Thus, in the control channel transmitting method used foradaptive radio link control, total throughput should be improved withoutdegradation in data channel transmission efficiency.

SUMMARY OF THE INVENTION

The present invention has been devised in consideration of this point,and an object of the present invention is to provide a control channeltransmitting method, a base station and a terminal by which totalthroughput can be improved without degradation in data channeltransmission efficiency.

In order to solve the above-mentioned problem, a control channeltransmitting method according to the present invention has a step ofselecting one control channel format from among a plurality of controlchannel formats having different information amounts according to apredetermined condition and a step of transmitting a control channelwith the use of the thus-selected control channel format.

Further, a base station according to the present invention has formatselecting means for selecting a control channel format from among aplurality of control channel formats having different informationamounts according to a predetermined condition and transmitting meansfor transmitting a control channel to a terminal with the use of thethus-selected control channel format.

Further, a terminal according to the present invention has controlchannel demodulating means for having a control channel format notifiedof from a base station which transmits a control channel with the use ofthe control channel format which is selected from among a plurality ofcontrol channel formats having different information amounts accordingto a predetermined condition, and demodulating the control channel thusreceived from the base station with the use of the thus-notified controlchannel format, and data channel demodulating means for demodulating adata channel received from the base station with the use of a result ofthe demodulation of the control channel thus carried out by the controlchannel demodulating means.

According to the present invention, one control channel format isselected from among a plurality of control channel formats havingdifferent information amounts according to a predetermined condition anda control channel is transmitted with the use of the thus-selectedcontrol channel format.

The predetermined condition may include the number of multiplexing usersin one transmission frame, a transmission/reception function mounted ina user terminal, QoS of a data channel, propagation path quality orsuch. By selecting one control channel format according to thepredetermined condition, it is possible to limit an information amountof the control channel, thus reduce the information amount of thecontrol channel, and thus, it is possible to avoid degradation in datachannel transmission efficiency.

According to the present invention, it is possible to provide a controlchannel transmitting method, a base station and a terminal for improvingtotal throughput without degradation in data channel transmissionefficiency.

BRIEF DESCRIPTION OF DRAWINGS

Other objects and further features of the present invention will becomemore apparent from the following detailed description when read inconjunction with the accompanying drawings:

FIG. 1 illustrates the number of codes available for data channels whenthe number of simultaneously multiplexing users is 1.

FIG. 2 illustrates the number of codes available for data channels whenthe number of simultaneously multiplexing users is 4.

FIG. 3 illustrates one example of the number of codes available for datachannels when the number of simultaneously multiplexing users is 4.

FIG. 4 illustrates another example of the number of codes available fordata channels when the number of simultaneously multiplexing users is 4.

FIG. 5 illustrates another example of the number of codes available fordata channels when the number of simultaneously multiplexing users is 3.

FIG. 6 shows a configuration of one embodiment of a system achieving acontrol channel transmitting method according to the present invention.

FIG. 7 shows a configuration of one embodiment of a formatselection/allocation part.

FIG. 8 shows a flow chart of one example of a processing procedure ofthe format selection/allocation part.

FIG. 9 shows a configuration of one embodiment of a format allocationpart.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1 base station    -   2 user terminal    -   10 format selection/allocation part    -   11 signaling generation part    -   12 control channel generation part    -   13 data channel generation part    -   14 multiplexing part    -   15 selection part    -   16 transmission part    -   17 propagation path measurement part    -   18 control channel demodulation part    -   19 data channel demodulation part    -   20 reception part    -   51 reception part    -   52 data channel demodulation part    -   53 signaling demodulation part    -   54 control channel demodulation part    -   55 propagation path measurement part    -   56 control channel generation part    -   57 format allocation part    -   58 data channel generation part    -   59 multiplexing part    -   60 transmission part    -   100 down-link control channel resource allocation part    -   101 down-link data channel resource allocation part    -   102 up-link control channel resource allocation part    -   103 up-link data channel resource allocation part    -   151 up-link control channel resource allocation part    -   152 up-link data channel resource allocation part

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, for easy understanding of the present invention, a principle ofthe present invention will now be described. According to the presentinvention, a plurality of control channel formats having differentinformation amounts, one thereof is selected according to apredetermined condition, for example, a situation (the number ofsimultaneously multiplexing users, a transmission/reception function (UEcapability) of a user terminal, QoS, propagation path quality or such),and then, the selected control channel format is used.

Here, an example in which two types of control channel formats, such asthose shown in Table 2 and Table 3, are prepared, will now be described.

TABLE 2 CONTROL CHANNEL FORMAT A NUM- BER OF CONTENTS BITS VARIABLERANGE MODULATING METHOD 2 4 TYPES (ANTENNA 1) (QPSK, 8PSK, 16QAM, 64QAM)MODULATING METHOD 2 4 TYPES (ANTENNA 2) (QPSK, 8PSK, 16QAM, 64QAM)MODULATING METHOD 2 4 TYPES (ANTENNA 3) (QPSK, 8PSK, 16QAM, 64QAM)MODULATING METHOD 2 4 TYPES (ANTENNA 4) (QPSK, 8PSK, 16QAM, 64QAM)ENCODING RATE 2 4 TYPES (1/3, 1/2, 2/3, 3/4) SPREADING FACTOR 3 8 TYPES(1, 2, 4, 8, 16, 32, 64, 128) CODE SET 128 MAXIMUM 128 CODES TOTAL 141

TABLE 3 CONTROL CHANNEL FORMAT B NUMBER CONTENTS OF BITS VARIABLE RANGEMODULATNG METHOD 1 2 TYPES (COMMON TO ANTENNAS) (QPSK, 16QAM) ENCODINGRATE 1 2 TYPES (1/2, 3/4) SPREADING FACTOR 2 4 TYPES (1, 4, 16, 64) CODESET 64 MAXIMUM 64 CODES TOTAL 68

A control channel format A shown in Table 2 has, as adaptive controlparameters, a modulating method (antenna 1) through a modulating method(antenna 4), an encoding rate, a spreading factor and a code set. Forexample, for the modulating method (antenna 1) through the modulatingmethod (antenna 4), four types of modulating methods (QPSK, 8PSK, 16QAM,64QAM) are set as variable ranges. The control channel format A shown inTable 2 is such that the number of types and the variable ranges of theadaptive control parameters are wide, and thus, the modulating methodcan be made variable for each antenna upon MIMO transmission, forexample.

On one hand, a control channel format B shown in Table 3 has, asadaptive control parameters, a modulating method (common for antennas),an encoding rate, a spreading factor and a code set. For example, themodulating method (common for antennas) is such that two types ofmodulating methods (QPSK and 16QAM) are set as a variable range. Thecontrol channel format B shown in Table 3 is such that, the types andthe variable range of the adaptive control parameters are limited incomparison to those of the control channel format A, and the number ofbits is approximately ½ of that of the control channel format A.

It is also possible to use the control channel format B for a userterminal compliant to MIMO transmission, when such a condition that amodulating method is not variable for each antenna, and the modulatingmethod is controlled in common to the antennas are allowed.

According to the present invention, when the number of simultaneouslymultiplexing users is small, the control channel format A having thelarge information amount is used, and thus, a larger benefit of theadaptive radio link control can be obtained, whereby total throughputcan be improved.

On one hand, according to the present invention, when the number ofsimultaneously multiplexing users is large, the control channel format Bhaving the smaller information amount is used, and thus, the informationamount of the control channel is limited. Then, the information amountof data channels is increased by an amount by which the informationamount of the control channel is thus reduced, and thus, it is possibleto avoid degradation in data channel transmission efficiency.

Description will now be made assuming a case of user multiplexing bymeans of CDMA. FIG. 3 illustrates one example showing the number ofcodes available for data channels when the number of simultaneouslymultiplexing users is 4.

In FIG. 3, the control channel format B having the information amountapproximately ½ of that of the control channel format A is used, andthus, two control channels (for two users) are multiplexed in onespreading code.

As a method of dividing in one spreading code, a method of using timeslots along a time direction or another method of using sub-carriersalong a frequency direction is available. It is noted that, FIG. 3 showsthe example in which time slots along a time direction are used, andthus, the two control channels are multiplexed in a time domain in onespreading code.

In the example of FIG. 3, as the number of codes necessary fortransmitting the control channels for four users is 2, the number ofcodes available for data channels increases to 6. Accordingly, in theexample of FIG. 3, in comparison to the example of FIG. 2 describedabove, the data channel transmission efficiency improves.

Further, other than the methods of multiplexing control channels in atime domain or a frequency domain, the number of multiplexing may beincreased in a code domain by increasing a spreading factor of thecontrol channels.

FIG. 4 illustrates another example showing the number of codes availablefor data channels when the number of simultaneously multiplexing usersis 4. In FIG. 4, the spreading factor of the control channels isdoubled, and the control channel format B having the information amountapproximately ½ of that of the control channel format A is used.Thereby, the number of codes available for data channels increases to 6.Accordingly, in the example of FIG. 4, in comparison to the case of FIG.2, the data channel transmission efficiency improves.

Further, the control channel format may be switched according to whetheror not a user terminal is compliant to MIMO transmission. FIG. 5 showsanother example showing the number of codes available for data channelswhen the number of simultaneously multiplexing users is 3.

In FIG. 5, the example is shown in which one user terminal compliant toMIMO transmission and other two user terminals not compliant to MIMOtransmission are mixed. In this case, the control channel format A isallocated to the user terminal compliant to MIMO transmission, while,the control channel format B is allocated to the user terminals notcompliant to MIMO transmission.

As a result of the control channel format B being allocated to the userterminals not compliant to MIMO transmission, two control channels (fortwo users) are multiplexed in one spreading code. As a result of thecontrol channel format A being allocated to the user terminal compliantto MIMO transmission, one control channel (for a single user) ismultiplexed in one spreading code.

Thus, for the user terminals not compliant to MIMO transmission, coderesources used for the control channels is limited, and thus, datachannel efficiency can be improved. For the user terminal compliant toMIMO transmission, adaptive radio link control is available for eachantenna, and thus, total throughput can be improved. Accordingly, in theexample of FIG. 5, transmission efficiency of data channels improves incomparison to the case of FIG. 2.

It is noted that the control channels shown in FIGS. 3 through 5 may becombined together appropriately. For example, in FIG. 5, the example isshown in which the two control channel formats B are multiplexed in thesignal spreading code in the time domain. However, they may bemultiplexed in a code domain as shown in FIG. 4, where the spreadingfactor of the control channels is doubled.

Further, changing of the control channel format to use according to QoSor propagation path quality different for each user is advantageous. Forexample, for a user terminal having low propagation path quality, and apropagation path condition fluctuates violently, the control channelformat A having the wider variable range of the adaptive radio linkcontrol should be used.

Further, for a user terminal having good propagation path quality and arelatively stable propagation path condition, the control channel formatB requiring the smaller information amount should be used. Further, fora user terminal requiring high QoS, i.e., requiring a high datatransmission rate, or a reduced transmission delay, the control channelformat A having the wider variable range of the adaptive radio linkcontrol, from which improvement in throughput is thus expected, shouldbe used.

Thus, according to the present invention, such control is carried outthat, the control channel format to use is selected according to asituation, and thus, transmission efficiency (total throughput) ismaximized.

The control is made mainly by a base station. The base station selectsthe control channel format, and notifies a user terminal of thethus-selected control channel format by means of signaling. The singlingshould be made at a time of connection to the user terminal, or everypredetermined time interval.

Further, in the signaling, not only the thus-selected control channelformat, but also a spreading factor and/or a spreading code of thecontrol channel, a time slot (for when multiplexing is made in a timedomain), a sub-carrier arrangement (for when multiplexing is made in afrequency domain), or such, are notified of, simultaneously. It is notedthat the present invention is applicable not only to down-linktransmission from the base station to the user terminal but also toup-link transmission from the user terminal to the base station in thesame manner.

Next, a best mode for carrying out the present invention will now bedescribed based on an embodiment with reference to figures. FIG. 6 showsa configuration of one embodiment of a system achieving a controlchannel transmitting method according to the present invention. Thesystem of FIG. 6 includes a base station 1 and a user terminal 2.

The base station 1 is configured to include a formatselection/allocation part 10, a signaling generation part 11, a controlchannel generation part 12, a data channel generation part 13, amultiplexing part 14, a selection part 15, a transmission part 16, apropagation path measurement part 17, a control channel demodulationpart 18, a data channel demodulation part 19 and a reception part 20.

The user terminal 2 is configured to include a reception part 51, a datachannel demodulation part 52, a signaling demodulation part 53, acontrol channel demodulation part 54, a propagation path measurementpart 55, a control channel generation part 56, a format allocation part57, a data channel generation part 58, a multiplexing part 59 and atransmission part 60.

First, a down-link control channel transmitting method from the basestation 1 to the user terminal 2 will now be described. The formatselection/allocation part 10 of the base station 1 selects a controlchannel format as described above, and determines allocation of controlchannels and data channels in a frame (multiplexing method). The numberof users to be multiplexed, information such as a transmission/receptionfunction of the user terminals, down-link QoS, down-link CQI (ChannelQuality Indicator) or such, is used for the control channel formatselection.

Format allocation information indicating the selected allocation of thecontrol channel format is notified of to the user terminal 2 assignaling information from the signaling generation part 11 via theselection part 15 and the transmission part 16. Further, the formatallocation information is notified of to the control channel generationpart 12 and the data channel generation part 13.

A control channel and data channels generated by the control channelgeneration part 12 and the data channel generation part 13 aremultiplexed by the multiplexing part 14 based on the format allocationinformation, and then, are transmitted to the user terminal 2 via thetransmission part 16.

Next, the signaling demodulation part 53 of the user terminal 2demodulates the signaling information (format allocation information)notified of from the base station 1 via the reception part 51, andnotifies the control channel demodulation part 54 of the down-linkcontrol channel format. Based on the down-link control channel formatnotified of from the signaling demodulation part 53, the control channeldemodulation part 54 demodulates the control channel. The controlchannel demodulation part 54 notifies the data channel demodulation part52 of down-link adaptive control parameters demodulated from the controlchannel.

The data channel demodulation part 52 uses the adaptive controlparameters notified of from the control channel demodulation part 54,and carries out demodulation of the data channels. Down-link CQI usedfor selecting the down-link control channel format is measured by thepropagation path measurement part 55 of the user terminal 2. Then, thedown-link CQI, together with up-link QoS, a transmission/receptionfunction of the user terminal 2, is transmitted to the base station 1 bymeans of an up-link control channel for the base station 1 from the userterminal 2.

Next, an up-link control channel transmitting method from the userterminal 2 to the base station 1 will now be described. The up-linkcontrol channel format is selected by the format selection/allocationpart 10 of the base station 1, the same as the down-link control channelformat. The number of users multiplexed, the transmission/receptionfunction of the user terminal, the up-link QoS, the up-link CQI (ChannelQuality Indicator) or such, is used for selecting the up-link controlchannel format.

The selected up-link control channel format is notified of to the userterminal 2 as signaling information, from the signaling generation part11, via the selection part 15 and the transmission part 16. Thesignaling demodulation part 53 demodulates the signaling informationnotified of from the base station 1 via the reception part 51, andnotifies the format allocation part 57 of the up-link control channelformat. The format allocation part 57 determines allocation of theup-link control channel and data channels (multiplexing method), andnotifies the control channel generation part 56 and the data channelgeneration part 58 of the format allocation information.

In the base station 1, the up-link control channel format selected bythe format selection/allocation part 10 is notified of to the up-linkcontrol channel demodulation part 18 therefrom. The control channeldemodulation part 18 demodulates the control channel, based on theup-link control channel format, notified of from the formatselection/allocation part 10. The control channel demodulation part 18notifies the data channel demodulation part 19 of the up-link adaptivecontrol parameters, demodulated from the control channel.

The data channel demodulation part 19 uses the adaptive controlparameters notified of from the control channel demodulation part 18,and demodulates the data channels. Up-link CQI used for selecting theup-link control channel format is measured by the propagation pathmeasurement part 17 of the base station 1.

It is noted that the measured up-link CQI is notified of to the formatselection/allocation part 10 from the propagation path measurement part17. Further, the up-link QoS, the down-link CQI and thetransmission/reception function of the user terminal 2, transmitted bymeans of the up-link control channel from the user terminal 2 to thebase station 1, are transmitted to the format selection/allocation part10.

Next, the format selection/allocation part 10 of the base station 1 willnow be described in further detail. FIG. 7 shows a configuration of oneembodiment of the format selection/allocation part. The formatselection/allocation part 10 is configured to include a down-linkcontrol channel resource allocation part 100, a down-link data channelresource allocation part 101, an up-link control channel resourceallocation part 102 and an up-link data channel resource allocation part103.

A processing procedure of the format selection/allocation part 10 ofFIG. 7 will now be described with reference to FIG. 8 which shows a flowchart. FIG. 8 shows the flow chart of one example of the processingprocedure of the format selection/allocation part.

In Step S1, the down-link control channel resource allocation part 100and the up-link control channel resource allocation part 102 allocateradio resources to the control channels of the respective user terminals2 according to the number of simultaneously multiplexing users and thetransmission//reception functions of the user terminals 2.

In Step S2, the down-link control channel resource allocation part 100and the up-link control channel resource allocation part 102 adjust theradio resources to be allocated to the control channels of therespective user terminals 2 according to CQI (reception quality,propagation path variation).

In Step S3, the down-link control channel resource allocation part 100and the up-link control channel resource allocation part 102 adjust theradio resources to be allocated to the control channels of therespective user terminals 2 according to QoS (transmission rates,required delays).

In Step S4, the down-link control channel resource allocation part 100and the up-link control channel resource allocation part 102 determinewhether or not data channel radio resources are sufficient. When theydetermine that the data channel radio resources are sufficient (Yes ofS4), Step S5 is then proceeded with.

In Step S5, the down-link data channel resource allocation part 101 andthe up-link data channel resource allocation part 103 allocate radioresources to data channels of the respective user terminals 2 accordingto CQI and QoS.

When such determination is made that the data channel radio resourcesare not sufficient (No in S4), Step S1 is then returned to. That is,until it is determined in Step S4 that the data channel radio resourcesare sufficient, the processing of Steps S1 through S4 is repeated.

From the processing procedure of FIG. 8, the above-described formatallocation information can be created, and thus, the format allocationinformation can be notified of to the signaling generation part 11, thecontrol channel generation part 12, the data channel generation part 13and the up-link control channel demodulation part 18.

Next, the format allocation part 57 of the user terminal 2 will now bedescribed in further detail. FIG. 9 shows a configuration of oneembodiment of the format allocation part. The format allocation part 57is configured to include an up-link control channel resource allocationpart 151 and an up-link data channel resource allocation part 152.

Based on the up-link control channel format notified of from thesignaling demodulation part 53, the up-link control channel resourceallocation part 151 allocates radio resources to the up-link controlchannel of the respective user terminal 2. Based on the up-link adaptivecontrol parameters notified of from the signaling demodulation part 53,the up-link data channel resource allocation part 152 allocates radioresources to the data channels of the respective user terminal 2.

Thus, the format allocation part 57 can create the above-describedformat allocation information, and thus, can notify the up-link controlchannel generation part 56 and the up-link data channel generation part58 of the format allocation information.

Thus, according to the present invention, since the number of bits ofthe control channel can be limited when the number of simultaneouslymultiplexing users increases, data channel transmission efficiency canbe improved. Further, since a larger benefit of adaptive radio linkcontrol can be obtained as a result of the control channel format to usebeing selected according to the transmission/reception function of theuser terminals 2 and/or the propagation path quality, total throughputcan be improved. Further, since degradation in data channel transmissionefficiency can be controlled, and the number of simultaneouslymultiplexing users can be increased, channel allocation can be carriedout more flexibly.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

What is claimed is:
 1. A method used by a terminal in a wirelesscommunication system, the method comprising: receiving a control channeltransmitted from a base station with use of a control channel formatselected from among a plurality of control channel formats, eachincluding modulation scheme information, according to whether MultipleInput Multiple Output (MIMO) transmission is applied or not, and whereina number of bits indicating a modulation scheme included in a controlchannel format to be selected when the MIMO transmission is applied isgreater than that included in a control channel format to be selectedwhen the MIMO transmission is not applied.